Animal litter composition containing silica gel and methods thereof

ABSTRACT

An animal litter composition comprising a mixture of an absorbant material such as clay and silica gel is disclosed. The Litter composition effectively absorbs liquid wastes and controls odors. Also disclosed are methods of making and using the litter composition.

This application is a continuation of U.S. patent application Ser. No.09/731,489, filed Dec. 7, 2000, the entire text of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates generally to animal litter compositions andmethods therefor and, more particularly, to novel animal littercompositions containing silica gel and an absorbant material and methodstherefor. The new compositions can be characterized as being sorptivefor moisture and undesirable odors.

(2) Description of the Related Art

Although a number of absorbant substances can function as animal litter,including recycled newspaper, paper sludge, corn cob granules, ricehulls, peanut hulls, sunflower hulls, alfalfa, cedar, sawdust, andlitters made from other organic plant materials, clay is the mostcommonly used material for litter-box fillers. Typical clays used arecalcium and sodium montmorillonites (including sodium bentonite),attapulgites, kaolins, and opal clay mixtures. All of these absorbanimal urine and help to cover the fecal waste and decrease odors.

Two types of clays have been used as animal litter. The gelling clays,such as sodium bentonite, form a clump when contacted with animal urineand can, therefore, be scooped out to prevent odor build up. These havebeen referred to as clumping litters which have grown in popularity toaccount for over half of all litter sales. Litters made from non-gellingclays, sometimes referred to as non-clumping litters, absorb the urine,but only the solid fecal matter can be scooped out. The non-clumpinglitters do not last long and are completely changed with fresh materialwhen the odor becomes too strong. This is also true for litters madefrom materials other than clay.

One disadvantage of clays, and most other materials used for animallitter, is that the odor is not effectively controlled by the littermaterial. Odors produced from animal urine and fecal materials includeammonia as well as a variety of organic sulfur materials. These typicalodorous gases associated with animal waste are not absorbed into claylitter materials, but are adsorbed onto the surface. As a result, theodorous gases volatilize back into the air creating an objectionableodor problem.

Various approaches have been tried to diminish the odor emanating fromlitter. In one such approach, fragrances have been used to mask odors.U.S. Pat. No. 4,020,156 to Murray et al. discloses fragrance-releasingcrystal beads as agents for controlling malodors in pet litter. U.S.Pat. No. 4,085,704 to Frazier discloses a vehicle impregnated with anodor control agent such as a perfume, flavor, fragrance or essence oil,for mixing with an absorbant litter material. The '704 patent disclosedthe use of silica gel as one possible carrier for the odor controllingagent, however, this reference neither disclosed nor suggested the useof the silica gel or any other carrier substance in absence of the odorcontrolling agent nor did this reference suggest the use of the carriersubstances for anything more than a vehicle of the odor controllingagent. In that regard, although many substances, including clay litters,can contribute at least some odor controlling activity by absorbing theodorous substances, it is likely that the prior impregnation of thecarrier with the odor controlling agent would have precluded the carrierfrom having any meaningful activity in absorbing the odorous substancesfrom animal urine and feces. Thus, while the use of odor masking agentscan be beneficial, their effectiveness is limited by virtue of theiracting to mask the odors rather than to eliminate the odors.

Others have used germicides to inhibit odor causing microorganisms. Forexample, U.S. Pat. No. 4,607,594 disclosed the use of a quaternary aminegermicide in a litter composition. U.S. Pat. No. 4,930,443 to Lowe etal. discloses an animal litter which includes a bacterial and fungalgrowth inhibitor, polyvinylpyrrolidone iodine complex, which isdissolved in water and sprayed onto the litter. Furthermore, variouschemicals have also been used to react with the odor-causing substances.U.S. Pat. No. 4,607,594 to Thacker discloses an animal litter usingbuffering agents such as a carbonate, a bicarbonate or hydrogenphosphate. U.S. Pat. No. 5,005,520 to Michael discloses the use of anoxidizing additive, such as sodium perborate in animal litter. SimilarlyReddy et al. disclosed the addition of urease negative bacteria to claypet litter to inhibit the growth of urease positive bacteria, therebyretarding formation of ammonia and other obnoxious odors (U.S. Pat. Nos.5,507,250 and 5,634,4310). None of these approaches, however, have beeneffective in preventing the development of odorous substances fromanimal litter containing animal waste products.

In another approach, animal litter can be made of substances which exerta sorptive effect on odorous gases. For example, U.S. Pat. No. 6,106,738to Woo et al. discloses spraying a cyclodextrin solution onto cat litterto absorb malodor. Similarly, zeolites have been used in cat litters toadsorb odorous gases. Cat litters which are 100% zeolite are currentlymarketed in the U.S. Alternatively, zeolites can be added to claylitters to control odor. For example, U.S. Pat. No. 4,437,429 toGoldstein et al. discloses the addition of zeolites to the claycomponent of animal litter to control odors from the litter. Zeolitesare, however, significantly more expensive than clay and, as a result,litters made from zeolite tend to be more expensive than clay litters.

A number of substances have been used to eliminate odors due to organicmolecular species in air filtering systems. Among these substances,silica gel has been used as a solid adsorbent for removing odors fromthe air. (see for example, U.S. Pat. Nos. 4,795,482, 4,604,110,4,534,775 and 4,517,308). In that regard, silica gel has been mentionedas one possible odor absorbing material for use in an air filtercomponent of a litter box assembly to remove undesirable odors. Thus,U.S. Pat. No. 5,044,325 to Miksitz discloses an animal litter box whichincludes a litter box tray and housing and an exhaust fan coupled withan odor absorbing filter assembly to deodorize the air before ventingthe air from the litter box.

Recently, silica gel has been employed as a litter box filler (see U.S.Pat. No. 5,970,915). The silica gel used was macroporous silica gelwhich was reported to effectively eliminate odors in addition toabsorbing moisture from the urine. A significant problem with the use ofsilica gel as an animal litter is that silica gel is substantially morecostly than clay litter box fillers. Although 100% silica gel has beenused as a litter to absorb odors, silica gel has not been used as acomponent of a litter composition in combination with clay litterbecause it has not heretofore been appreciated that silica gel couldserve as an effective odor control agent when mixed with a clay litter.Thus there remains a continuing need for new animal litter compositionswhich control odors in addition to absorbing liquid animal wastematerials.

SUMMARY OF THE INVENTION

Accordingly, the inventors herein have succeeded in discovering thatsilica gel can be combined with an absorbant material, preferably clay,in an animal litter composition. Surprisingly, the animal littercomposition containing the silica gel is effective in controlling odor.

Thus, in one embodiment the present invention is directed to an animallitter composition comprising a mixture of an absorbant material andsilica gel. The silica gel is present in the composition in an amounteffective in controlling odor in the composition. By controlling odor,it is meant that the amount of detectable, odorous substances emanatingfrom the litter upon use of the litter by the animal, are diminished.Preferably, the silica gel is a Type C silica gel. The silica gel ispresent in the composition in an amount, preferably, from about 5% toabout 50% (w/w). By “w/w” in the context of a percent of a composition,it is meant that the amount of a component of a composition iscalculated as the ratio of the weight of that component divided by thetotal weight of the composition multiplied by 100 to obtain the percentvalue. The term “about” as used herein is intended to indicate a rangeof values of 10% greater and lesser than the indicated value. Thus,about 5% is intended to encompass a range of values from 4.5% to 5.5%.

Preferably, the silica gel is in the form of particles. The silica gelparticles have an average pore diameter, preferably, from about 8 nm. toabout 10 nm.

The absorbant material of the animal litter composition is, preferably,clay. The clay of the present invention is, preferably, selected fromthe group consisting of a smectite, an attapulgite, a kaolin, an opalclay and mixtures thereof. The smectite is preferably a calciummontmorillonite or a sodium bentonite. The amount of clay in the animallitter composition is, preferably, from about 50% to about 95% (w/w).Both the silica gel and clay components of the animal litter compositionare in the form of particles of similar average size and shape so thatno separation occurs upon preparation and handling, i.e. the more denseclay particles do not tend to settle to the bottom of the compositionand/or the less dense silica gel particles do not tend to rise to thetop of the composition. Thus, the clay particles, preferably, have anaverage size and shape sufficiently similar to the average size andshape of the silica gel particles to prevent separation of the clayparticles and silica gel particles. Preferably, the average size of theclay particles is no more than 10% greater or lesser than the averageparticle size of the silica gel particles. Preferably, at least 90%(w/w) of the clay comprises clay particles having a diameter of fromabout 0.6 mm to about 3.4 mm and at least 90% (w/w) of the silica gelparticles comprises silica gel particles having a diameter of from about1 mm to about 5 mm.

In certain aspects of this embodiment, the composition can furthercomprise an odor masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor masking agent may beincorporated into a carrier which may be silica gel; however, when theodor masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.

In another embodiment, the present invention is directed to a granularcomposition. The composition comprises clay and silica gel. The silicagel is not impregnated with an odor-masking agent. As a result, thesilica gel can serve an odor-controlling function in the composition.The silica gel is, preferably, Type C silica gel and the compositioncomprises, preferably, from about 5% to about 50% (w/w) silica gel. Thesilica gel is, preferably, in the form of particles having an averagepore diameter from about 8 nm. to about 10 nm.

Preferably, the absorbant material is clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The smectite is preferably a calcium montmorillonite ora sodium bentonite. The composition, preferably, comprises from about50% to about 95% (w/w) clay. Both the clay and silica gel are in theform of particles. The clay particles are, preferably, have an averagesize and shape sufficiently similar to average size and shape of thesilica gel particles to prevent separation of the clay particles andsilica gel particles. Preferably, the average size of the clay particlesis no more than 10% greater or lesser than the average particle size ofthe silica gel particles. Preferably, at least 90% (w/w) of the claycomprises clay particles having a diameter of from about 0.6 mm to about3.4 mm, and at least 90% (w/w) of the silica gel particles comprisessilica gel particles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the composition can furthercomprise an odor masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor-masking agent may beincorporated into a carrier which may be silica gel, however, when theodor masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.

Another embodiment of the present invention is directed to an animallitter composition which comprises an absorbant material and silica gel.The silica gel is present in an amount selected to control odor in thecomposition. Reference to the silica gel being selected to control odoris intended to mean that the silica gel is incorporated into thecomposition on the basis of its exerting an odor-controlling effect.Such selecting may be, in whole or in part, comprised of determiningthat the silica gel in the composition exerts an odor-controllingeffect.

The silica gel is, preferably, Type C silica gel and the compositioncomprises, preferably, from about 5% to about 50% (w/w) silica gel. Thesilica gel is, preferably, in the form of particles having an averagepore diameter from about 8 nm. to about 10 nm.

The absorbant material is, preferably, clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The smectite is preferably a calcium montmorillonite ora sodium bentonite. The composition, preferably, comprises from about50% to about 95% (w/w) clay. Both the clay and silica gel are in theform of particles. The clay particles, preferably, have an average sizeand shape sufficiently similar to average size and shape of the silicagel particles to prevent separation of the clay particles and silica gelparticles. Preferably, the average size of the clay particles is no morethan 10% greater or lesser than the average particle size of the silicagel particles. Preferably, at least 90% (w/w) of the clay comprises clayparticles having a diameter of from about 0.6 mm to about 3.4 mm and atleast 90% (w/w) of the silica gel particles comprises silica gelparticles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the composition can furthercomprise an odor masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor-masking agent may beincorporated into a carrier which may be silica gel, however, when theodor masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.Alternatively, all of the silica gel present in the composition can bepartially impregnated with an odor masking agent, however, the silicagel, nevertheless, exerts an odor-controlling function in addition tobeing a carrier for the odor-masking agent. Furthermore, in all aspectsof this embodiment, the silica gel is selected, in whole or in part, onthe basis of the silica gel exerting an odor-controlling effect whetheror not the silica gel also serves an additional function of acting as acarrier for an odor-masking agent.

Another embodiment of the present invention is directed to a kit. Thekit comprises silica gel and instructions for addition of the silica gelto an animal litter composition in an amount effective in controllingodor in the composition. The components of the kit are packaged in acontainer. The instructions can be in the form of an instruction manual,an enclosed pamphlet or product insert, printed instructions on thepackaging container or any form of written instructions accompanying thesilica gel component of the kit. Preferably, the silica gel is Type Csilica gel comprising particles having an average pore diameter fromabout 8 nm to about 10 nm. The instructions indicate that the silica gelis to be added to an animal litter composition. The amount of silica gelto he added to the animal litter composition can be indicated to be avalue of from about 5% to about 50% (w/w) silica gel. Preferably, theinstructions call for the addition of the silica gel to a clay animallitter composition. In an alternative embodiment, the kit can comprisesilica gel, an adsorbant material and instructions for mixing the silicagel with the adsorbant material. Preferably, the clay is selected fromthe group consisting of a smectite, an attapulgite, a kaolin, an opalclay and a mixture thereof. The smectite is preferably a calciummontmorillonite or a sodium bentonite. Preferably, the instructionsindicate that the silica gel is to be added to from about 50% to about95% (w/w) clay. In certain aspects of this embodiment, the clay andsilica gel are both in the form of particles of similar average size andshape. Preferably, the average size of the clay particles is no morethan 10% greater or lesser than the average particle size of the silicagel particles. It is also preferred that at least 90% (w/w) of the claycomprises clay particles have a diameter of from about 3.4 mm to about0.6 mm, and at least 90% (w/w) of the silica gel particles comprisessilica gel particles having a diameter of from about 5 mm to about 1 mm.

The kit can further comprising an odor masking agent which can be aperfume, a fragrance, or an essential oil.

In another embodiment, the present invention is directed to a method forcontrolling odor in an animal litter. The method comprises adding silicagel to an animal litter comprising an absorbant material. The silica gelis added in an amount effective in controlling odor. Preferably, thesilica gel is Type C silica gel and the composition comprises,preferably, from about 5% to about 50% (w/w) silica gel. The silica gelis, preferably, in the form of particles having an average pore diameterfrom about 8 nm. to about 10 nm.

The absorbant material is, preferably, clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The smectite is preferably a calcium montmorillonite ora sodium bentonite. The composition, preferably, comprises from about50% to about 95% (w/w) clay. Both the clay and silica gel are in theform of particles. The clay particles, preferably, have an average sizeand shape sufficiently similar to average size and shape of the silicagel particles to prevent separation of the clay particles and silica gelparticles. Preferably, the average size of the clay particles is no morethan 10% greater or lesser than the average particle size of the silicagel particles. Preferably, at least 90% (w/w) of the clay comprises clayparticles having a diameter of from about 0.6 mm to about 3.4 mm and atleast 90% (w/w) of the silica gel particles comprises silica gelparticles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the method further comprisesadding an odor-masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor-masking agent may beincorporated into a carrier which may be silica gel, however, when theodor masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.

Another embodiment of the present invention is directed to a method forcontrolling odor in an animal litter. The method comprises selectingsilica gel on the basis of the silica gel providing odor control andadding the silica gel to an animal litter containing an absorbantmaterial. Selecting the silica gel on the basis of its exerting anodor-controlling effect may be, in whole or in part, comprised ofdetermining that the silica gel in the composition exerts anodor-controlling effect.

The silica gel is, preferably, Type C silica gel and the compositioncomprises, preferably, from about 5% to about 50% (w/w) silica gel. Thesilica gel is, preferably, in the form of particles having an averagepore diameter from about 8 nm. to about 10 nm.

The absorbant material is, preferably, clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The smectite is preferably a calcium montmorillonite ora sodium bentonite. The animal litter composition, preferably, comprisesfrom about 50% to about 95% (w/w) clay. Both the clay and silica gel arein the form of particles. The clay particles, preferably, have anaverage size and shape sufficiently similar to average size and shape ofthe silica gel particles to prevent separation of the clay particles andsilica gel particles. Preferably, the average size of the clay particlesis no more than 10% greater or lesser than the average particle size ofthe silica gel particles. Preferably, at least 90% (w/w) of the claycomprises clay particles having a diameter of from about 0.6 mm to about3.4 mm, and at least 90% (w/w) of the silica gel particles comprisessilica gel particles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the method can further compriseadding an odor-masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor masking agent may beincorporated into a carrier which may be silica gel, however, when theodor masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.Alternatively, all of the silica gel present in the composition can bepartially impregnated with an odor masking agent, however, the silicagel, nevertheless, exerts an odor-controlling function in addition tobeing a carrier for the odor-masking agent. Furthermore, in all aspectsof this embodiment, the silica gel is selected, in whole or in part, onthe basis of the silica gel exerting an odor-controlling effect whetheror not the silica gel also serves an additional function of acting as acarrier for an odor-masking agent

Another embodiment of the present invention is directed to a method formaking an odor-controlling animal litter composition. The methodcomprises combining an absorbant material and an amount of silica gelamount effective in controlling odor. Preferably, the silica gel is TypeC silica gel and the composition comprises, preferably, from about 5% toabout 50% (w/w) silica gel. The silica gel is, preferably, in the formof particles having an average pore diameter from about 8 nm. to about10 nm.

The absorbant material is, preferably, clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The composition, preferably, comprises from about 50%to about 95% (w/w) clay. Both the clay and silica gel are in the form ofparticles. The clay particles are, preferably, have an average size andshape sufficiently similar to average size and shape of the silica gelparticles to prevent separation of the clay particles and silica gelparticles. Preferably, the average size of the clay particles is no morethan 10% greater or lesser than the average particle size of the silicagel particles. Preferably, at least 90% (w/w) of the clay comprises clayparticles having a diameter of from about 0.6 mm to about 3.4 mm and atleast 90% (w/w) of the silica gel particles comprises silica gelparticles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the method can further compriseadding an odor masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor-masking agent may beincorporated into a carrier which may be silica gel, however, when theodor-masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.

In another embodiment, the present invention is directed to a method formaking an odor-controlling animal litter composition. The methodcomprises selecting silica gel on the basis of the silica gel providingodor control and adding the silica gel to an animal litter containing anabsorbant material. Selecting the silica gel on the basis of itsexerting an odor-controlling effect may be, in whole or in part,comprised of determining that the silica gel in the composition exertsan odor-controlling effect.

The silica gel is, preferably, Type C silica gel and the compositioncomprises, preferably, from about 5% to about 50% (w/w) silica gel. Thesilica gel is, preferably, in the form of particles having an averagepore diameter from about 8 nm. to about 10 nm.

The absorbant material is, preferably, clay which may be, but is notlimited to, a smectite, an attapulgite, a kaolin, an opal clay or amixture thereof. The smectite is preferably a calcium montmorillonite ora sodium bentonite. The animal litter composition, preferably, comprisesfrom about 50% to about 95% (w/w) clay. Both the clay and silica gel arein the form of particles. The clay particles, preferably, have anaverage size and shape sufficiently similar to average size and shape ofthe silica gel particles to prevent separation of the clay particles andsilica gel particles. Preferably, the average size of the clay particlesis no more than 10% greater or lesser than the average particle size ofthe silica gel particles. Preferably, at least 90% (w/w) of the claycomprises clay particles having a diameter of from about 0.6 mm to about3.4 mm, and at least 90% (w/w) of the silica gel particles comprisessilica gel particles having a diameter of from about 1 mm to about 5 mm.

In certain aspects of this embodiment, the method can further compriseadding an odor masking agent which is preferably, a perfume, afragrance, or an essential oil. The odor-masking agent may beincorporated into a carrier which may be silica gel, however, when theodor-masking agent is present and silica gel is used as a carrier, atleast some of the silica gel component of the composition has noadsorbed odor-masking agent and exerts an odor-controlling function.Alternatively, all of the silica gel present in the composition can bepartially impregnated with an odor masking agent, however, the silicagel, nevertheless, exerts an odor-controlling function in addition tobeing a carrier for the odor-masking agent. Furthermore, in all aspectsof this embodiment, the silica gel is selected, in whole or in part, onthe basis of the silica gel exerting an odor-controlling effect whetheror not the silica gel also serves an additional function of acting as acarrier for an odor-masking agent.

Among the several advantages achieved by the present invention,therefore, may be noted the provision of an animal litter compositionand a granular composition that have an odor-controlling silica gelcomponent; the provision of a clay-based animal litter composition whichcan be used for a longer period of time by virtue of its containing anodor-controlling silica gel component; the provision of an animal littercomposition which exerts an odor-controlling effect at a lower cost thana litter of 100% silica gel; the provision of an odor-controllingadvantages of silica gel and the water absorbing and wicking effect ofclay in an animal litter composition; the provision of kits forpreparing an odor-controlling litter composition; and the provision ofmethods of making and methods of using such animal litter compositions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is based upon the discovery that silica gel can beincorporated into an animal litter composition containing an absorbantmaterial such as clay, to effectively control odor as the littercomposition is used. The silica gel component can be any of a variety ofsilica gels suitable for adsorbing organic materials typically found inanimal litter upon use by the animal. Such organic materials includeorganic sulfur materials.

Silica gels can be classified according to pore size as Type A, Type B,Type C or wide pore silica gel. The average pore sizes range from about18 to about 120 angstrom (1.8 to 12 nm.) according to the silica geltype. Preferably, the silica gel of the present invention is amacroporous silica gel of Type B, Type C or wide pore silica gel. Type Asilica gel tends to have a narrow pore size and is less preferred. Mostpreferably, the silica gel of the present invention is Type C silica gelhaving an average pore diameter in the range of from about 80 to about100 angstroms, i.e., about 8 to about 10 nm.

The silica gel is comprised of particles, preferably, in the form ofeither rounded beads or irregularly shaped granules. Among differentbatches of silica gels used in the present invention the silica gelparticles may have average particle diameters, preferably, from about0.5 to about 10 mm and more preferably from about 1 to about 5 mm.Within batches of silica gel, it is desirable that at least about 80% ofthe particles have a diameter from about 1 to about 5 mm, morepreferably at least about 90% of the particles have a diameter fromabout 1 to about 5 mm and most preferably at least about 95% or more ofthe particles have a diameter from about 1 to about 5 mm.

The amount of silica gel in the compositions is preferably, about 1%(w/w); more preferably, about 2.5% (w/w); more preferably, about 5%(w/w); more preferably, about 10%; more preferably, about 15% (w/w);more preferably, about 20% (w/w); more preferably, about 25% (w/w); morepreferably, about 30% (w/w); more preferably, about 40% (w/w); and morepreferably about 50% (w/w); more preferably, about 60% (w/w); morepreferably about 70% (w/w) or greater.

The silica gel component of the composition of the present inventionprovides odor control for the composition such that when the compositionis used as an animal litter, the amount of odorous substances detectableemanating from the composition is diminished. While not intending to bebound by any particular mechanism of action, it is believed that theodor controlling function of the silica gel results from adsorption ofthe odorous substances on to pore surfaces of the silica gel. Thisadsorption may also be associated with a decomposition of the odoroussubstances. Nevertheless, regardless of the specific mechanism ofaction, the silica gel of the present invention serves to control odorin the composition as it is used by the animal, i.e., the silica geldecreases the odorous substances escaping from the composition after itis used by the animal.

In certain embodiments, the silica gel component of the composition isselected on the basis of the silica gel providing odor control. Suchselecting can involve, in whole or in part, determining that the silicagel component of the composition exerts an odor controlling function.This can also involve testing for the decrease in odor production by thecomposition or it can involve no more than recognizing that the silicagel component functions to control odors.

Testing for the odor controlling function can be by any method known inthe art. For example any of the hedonic testing systems can be used suchas application of the nine point hedonic scale. Typically such testingmethods use a panel of individuals, preferably trained individuals, whoscore the organoleptic quality of odor for a particular composition on astandard scale (see, for example, Stone and Sidel in Sensory EvaluationPractices, Academic Press, Orlando, 1985, pp. 58-86, 227-252). Thecollective values obtained from the panel indicate whether the odor ofthe composition is objectionable and comparison with controlcompositions not containing the silica gel can indicate whether the odoris diminished by the silica gel component.

The compositions of the present invention also contain an absorbantmaterial. The absorbant material serves to absorb the liquid componentsof animal wastes. By way of comparison, animal litter compositionscontaining silica gel and no other absorptive material, can becomesaturated with animal urine causing a pooling of liquid waste and odorbuild up in that area of the litter material. In contrast, the littermaterial of the present invention which is a mixture of silica gel andabsorptive material. This component of clay or other absorptive materialserves to effectively wick the moisture away to avoid the formation ofliquid pooling.

A number of absorbant materials are known in the art. Among theabsrobant materials that can be used clay is most commonly used and clayis the preferred absorbant of the present invention. Nevertheless avariety of other absorbant materials can be used including, but notlimited to such adsorbant materials as recycled newspaper paper sludge,corn cob granules, rice hulls, peanut hulls, sunflower hulls, alfalfa,cedar, sawdust, litters made from other organic plant materials and thelike.

A number of types of clays can be used as the absorbant material in thecompositions of the present invention. Typical clays used are smectites(including calcium montmorillonites and sodium bentonite), attapulgites,kaolins, and opal clay mixtures.

The smectite clays are hydrated aluminum magnesium silicates in the formof either calcium or sodium salts. The term “montmorillonite” is usedherein in reference to the calcium smectite clays, i.e. calciummontmorillonite clays, and the term “bentonite” is used herein inreference to the sodium smectite clays, i.e. sodium bentonite clays.Both calcium montmorillonite and sodium bentonite clays are commonlyused as pet litter. Calcium montmorillonite is an acid-activatable clay.Such acid activation can increase the surface area and enhance theabsorptive properties of calcium montmorillonite. Sodium bentonite, alsoknown as Wyoming or western bentonite, tends to be less absorptive thancalcium montmorillonite. Sodium bentonite and, to a lesser extent,calcium montmorillonite, both swell upon absorbing water to formgel-like masses. The agglomerations of sodium bentonite clay and moistanimal wastes form isolatable clumps which can be readily removed fromthe litter composition.

Attapulgite clay, which is hydrous magnesium aluminum silicate, is alsocommonly used in pet litters. Kaolin, or china clay, and sedimentaryopal clay mixtures can also be used in animal litter compositions.Kaolin is a hydrous aluminum silicate of the Kaolinite mineral group.Opal clay contains a grated amount silicon dioxide than bentonite andprovides a high porosity and high absorption capacity.

Preferably, the clay component of the compositions of the presentinvention are, preferably, in an amount of, preferably, about 30% (w/w);more preferably, about 40% (w/w); more preferably, about 50% (w/w); morepreferably, about 60% (w/w); more preferably, about 70% (w/w); morepreferably, about 75% (w/w); more preferably, about 80% (w/w) (w/w);more preferably, about 85% (w/w); more preferably, about 90% (w/w); morepreferably, about 95% (w/w) or greater.

Both the silica gel and the clay components are, preferably, in the formof particles. Typically, granular particles of calcium montmorilloniteclay that may be used in the compositions of the present invention havean average diameter of from about 0.2 mm to about 10 mm, more preferablyfrom about 0.5 to about 5 mm and more preferably from about 1 mm toabout 2.5 mm and the silica gel particles have a similar size range.Thus, in one aspect of the present invention, both the silica gel andthe clay components are in the form of particles of a similar averagesize so as to avoid settling and separation of the clay particles fromthe silica gel particles.

Clay particles tend to be more dense than silica gel particles. Forexample, typical silica gel has a free fall bulk density of 20-30lbs./cu. ft. whereas typical clays for animal litter have a bulk densityof 30-70 lbs./cu.ft. For example, attapulgite clays from Georgia and thesoutheast have a bulk density of 30-38 lb./cu.ft.; calciummontmorillonite or calcium smectites have a bulk density of 42-52lb./cu/ft.; and sodium bentonite has a bulk density of 62-70 lb./cu.ft.

As a result of the difference in the densities of silica gel and clayparticles, mixtures could tend to separate into its separate componentsduring preparation and handling, i.e. the clay particles could settle tothe bottom and the silica gel particles could tend to rise to the top ofthe mixture.

It is believed that this separation can be diminished by selecting clayparticles and silica gel particles of a similar size. Thus, it ispreferred that both the silica gel and clay components of the animallitter composition are in the form of particles of similar average sizeso as to diminish any separation due to the different densities ofsilica gel and clay. This can be achieved in the present invention byselecting silica gel and clay components such that the average size ofthe clay particles is, preferably, no more than 20% greater or lesserthan the average particle size of the silica gel particles; morepreferably, the average size of the clay particles is no more than 15%greater or lesser than the average particle size of the silica gelparticles; more preferably, the average size of the clay particles is nomore than 10% greater or lesser than the average particle size of thesilica gel particles; and more preferably, the average size of the clayparticles is no more than 5% greater or lesser than the average particlesize of the silica gel particles.

The selection of silica gel and clay particles of similar size may alsobe achieved by selecting silica gel and clay components which each havea ranges of particle sizes overlapping each other. Preferably, at least90% (w/w) of the clay comprises clay particles have a diameter within arange that overlaps the range of diameters of particles which compriseof 90% (w/w) of the silica gel. In one preferred embodiment, at least90% (w/w) of the clay comprises clay particles have a diameter of fromabout 0.6 mm to about 3.4 mm and at least 90% (w/w) of the silica gelparticles comprises silica gel particles having a diameter of from about1 mm to about 5 mm.

Shape is also believed to be a factor in that granular or irregularlyshaped silica gel particles tend to mix more easily with irregularlyshaped particles. It has been observed that silica gel made intospherical beads does not mix well or stay mixed with granular clayparticles. There are even slight differences observed for granularproducts in which clay granules that are made flatter from thegranulation process are more difficult to mix with the more bulky silicagel particles. For example, processed clay from California such asmonterey shale, has more rounded or bulkier granules and seems to mixmore easily with similarly shaped silica gel granules than the flatterclay granules such as calcium montmorillonite from Missouri.

In another aspect of the present invention, the composition, in certainembodiments, can further comprise an odor masking agent. By odor maskingagent it is meant that the agent acts to diminish perception of the odorwithout necessarily altering the amount of odor released from the animallitter upon its use. Any of a variety of perfumes, fragrances andessential oils can be used as the odor masking agent including, but notlimited to, heliotropine, lemongrass oil, 1,8-cineole, terpineol, listeacubeba oil, citronella oil, cedarwood oil, ginger oil, eucalyptus oil,orange oil, andrane, benzyl acetate, benzyl benzoate, camphor oil,carvone, cedrole, cedrone, cedryl acetate, cedryl methyl ether, cineol,coumarin, diphenylide, ethyl butyrate, jasmin sambac chine concrete,linalool, methyl benzoate, musk ambrette, musk jinghai, musk ketone,musk xylol, phenyl ethyl alcohol, raspberry ketone, roselin, spearmintoil, borneol, sandenol, vanillin, wintergreen oil and combinationsthereof. The odor masking agent can also be any of a number of organicsubstances exhibiting desirable aromatic organoleptic characteristics.Such organic substances include alcohols, aldehydes, esters, ketones,ethers, phenols, lactones, carboxylic acids, nitrites and the like.Typical chemical substances in certain floural fragrances include1,4-dimethoxy benzene, 2-phenyl nitroethane, 3,5-dimethoxy toluene,4-keto β-ionone, 4-terpineol, 5-dimethyl 2-ethyl pyrazine,α-caryophyllene, α-elemene, α-farnesene, α-terpineol, anisic aldehyde,anisyl acetate, β-damascenone, β-lonone, β-pinene, benzaldehyde, benzylacetate, benzyl alcohol, C₁₅ hydrocarbons, caryophyllene, cis 3-hexenylacetate, cis 3-hexenyl butyrate, cis jasmone, cis/trans ocimene,citronellol, cyclocitral, δ-dodecalactone, dihydro β-ionol, dihydroβ-ionone, ethyl jasmonate, eugenol, geraniol, geranyl acetone,heptadecadiene, hexyl acetate, indole, jasmin lactone, lilac alcohols,lilac aldehydes, limonene, linalool, linalool oxides, methyl5-hepten-2-1, methyl anthranilate, methyl benzoate, methyl salicylate,n-hexanol, n-pentadecane, nerol-geraniol, nerolidol, p-dimethoxybenzene, phenyl ethyl acetate, phenyl ethyl acetate, phenyl ethylacetate, t-terpinene, trans β-ocimene, pinene, terpineol andcombinations thereof.

The odor-masking agent may be encapsulated such as in encapsulatedfragrance powders or incorporated into a carrier system, a number ofwhich are known in the art (See, for example, U.S. Pat. Nos. 4,085,704;4,898,727; 4, 561,997; 5,240,699; 5,035,886; and 5,336,665). In certainembodiments, silica gel can be used as a carrier. However, in thoseembodiments in which silica gel is used as a carrier for the odormasking agent, the composition contains at least some silica gel whichhas no adsorbed odor-masking agent so that the silica gel can exert anodor-controlling function. Alternatively, in other embodiments, thesilica gel may be only partially impregnated with an odor-masking agentso that the silica gel particles can still act to control odors. Thiswould be the case if at least a portion of the adsorptive sites in thesilica gel particles remain free to adsorb odorous substances from theanimal waste materials and allow the silica gel to exert anodor-controlling function.

Additional components can also be added to the animal litter compositionincluding dust control agents, antimicrobial agents, coloring agents,guar gum and the like.

The present invention also encompasses kits suitable for preparing ananimal litter composition. The kit can comprise an amount of silica gelwith instructions for addition of the silica gel to an adsorbant littermaterial, preferably a clay litter material. The kit can also containsilica gel and clay litter material in separate containers along withinstructions for addition of the silica gel to the absorbant littermaterial. The instructions can be in the form of an instruction manual,a product brochure or insert, written instructions on a packagingcontainer, or any form of medium for communication of such instructions,preferably, in written form.

The present invention is further directed to methods of making and usingthe compositions of the present invention. Thus, in one embodiment, thepresent invention is directed to a method for controlling odor in ananimal litter. The method comprises adding silica gel to an animallitter comprising an absorbant material, preferably clay. The silica gelis added in an amount effective in controlling odor. In an alternativeembodiment, the method can comprise selecting silica gel on the basis ofthe silica gel providing odor control and adding the silica gel to ananimal litter containing an absorbant material. Selecting the silica gelon the basis of its exerting an odor-controlling effect may be, in wholeor in part, comprised of determining that the silica gel in thecomposition exerts an odor-controlling effect.

The present invention is also directed to a method for making anodor-controlling animal litter composition. The method comprisescombining an absorbant material and an amount of silica gel amounteffective in controlling odor. In an alternative embodiment, the methodcan comprise selecting silica gel on the basis of the silica gelproviding odor control and adding the silica gel to an animal littercontaining an absorbant material. Selecting the silica gel on the basisof its exerting an odor-controlling effect may be, in whole or in part,comprised of determining that the silica gel in the composition exertsan odor-controlling effect.

INDUSTRIAL APPLICATION

The present invention provides new compositions and methods based uponthe discovery that silica gel can be combined with an adsorbantmaterial, preferably a clay, to produce an animal litter composition.The silica gel functions in an odor-controlling manner and the clayserves to absorb liquids and to act to wick the liquids away from thesilica gel. Thus the composition not only absorbs liquid waste materialsdeposited by the animal, but it also effectively controls odors. Incertain embodiments, a clumping clay is used so that the animal wastematerials are agglomerated to facilitate their removal. The invention isdirected to compositions suitable for use as animal litters as well asto methods of making and using the animal litter compositions.

Preferred embodiments of the invention are described in the followingexamples. Other embodiments within the scope of the claims herein willbe apparent to one skilled in the art from consideration of thespecification and the examples that follow or from practice of theinvention as disclosed herein.

GENERAL TESTING PROCEDURES

The general testing procedures used in the examples below are asfollows.

Testing Environment

The sensory lab is maintained at 75° F. and with positive pressureventilation to maintain an odor-free environment. The lab containsbooths for sensory testing of odors. Exhaust fans in each booth removeany odors that may escape from samples being evaluated.

All materials in the lab including counters, partitions, walls, etc. areodor-free.

The testing area is maintained quiet and free from distractions.Insulated ceiling tiles are used to reduce noise from surrounding areas.

The booths allow the panelists to evaluate samples without distractionsamong panelists. Panelists move from booth to booth to evaluate samples.No chairs are used and a waiting room is used as a buffer between thebooths and hallway.

Panelists

Twelve to eighteen screened and trained panelists are used for eachtest. Panelists are screened for odor discrimination abilith and odorrecognition. Panelists are trained for attribute rating as suggested inGuidelines for the Selection and Training of Sensory Panel Members, ASTMpublication 758.

Samples

One Time Hand Treatment: If samples are to be hand treated, onerectangular box (1.5″ wide×12″ long×3.5″ deep) per treatment variable isprepared and treated. The litter sample is stirred thoroughly to ensurea homogenous mixture in each box. A volume equivalent to 4.5 poundsscoop litter is placed in each box. Eight 20-gram fecal cubes are placeon top of the litter. One hundred and sixty milliliters female urine ispoured over the fecal cubes wetting as much of the litter as possible. Avolume equivalent to 0.5 pounds scoop litter is used to cover the fecalcubes and wet litter. Boxes are left uncovered for 5 days. No furtherwaste material are added to the box. On the sixth day, litter is cleanedof fecal material and urine clumps (if possible).

One day prior to sensory evaluation the following is done.

a. Litter is stirred thoroughly to ensure a homogenous mixture in eachbox.

b. If used, duplicate boxes are combined into one sample.

c. Litter is passed through the splitter, recombined, passed through thesplitter a second time and recombined.

d. The recombined samples are split into three or four equal volumesamples by using the splitter.

e. Each split sample is put into urine specimen cups. Other samplecontainers could be used if dictated by the test purpose.

f. Each specimen cup is covered with a lid.

g. Sample containers are identified with 3-digit random codes.

h. Samples are placed in the testing booths the day before testing innumerical order.

Test Procedure

A balanced block test design is used when possible. Replicates are usedfor each variable when possible. Panelists rate aroma intensities ofeach sample. Generally fecal/urine, ammonia and/or fragrance aromas arerated. A 6-inch line scale with indented anchors labeled “weak” and“strong” is used.

Panelists are instructed to use the following sniffing procedures:

(1) 2-3 quick sniffs

(2) Mouth closed during sniffing

(3) Lid replaced immediately after sniffing

(4) Nose cleared by smelling ground coffee, if necessary

Panelists evaluate the samples in the order they are listed on theirscorecards. Panelists are instructed to take a 5 minute break betweentests or after every 10-12 samples. Descriptive analysis is most oftenused with the trained panelists. However, as the test purpose dictates,differences or ranking tests could also be used. The ranking tests canbe reported as individual ranking scores or as a ranking sum. In allmethods, standard sensory procedures are used to ensure reliable andvalid data.

Data Analysis

Analysis of variance, ranks, mean score differences and Duncan'smultiple comparison test can be used to analyze data. (for review oftesting and analysis system, see ASTM Manual Series: MNL 26 revison ofSTP434, 1996)

EXAMPLE 1

This example illustrates the odor-controlling effect of silica gel at1%, 5%, 10% and 20% in a mixture with a calcium montmorillonite claylitter obtained from Bloomfield, Mo.

Two different grades of silica gel were evaluated: 6-12 mesh desiccantgrade silica gel obtained from Fisher Scientific Co. (St. Louis, Mo.)and LITTER PEARLS (Harvest Ventures, Inc., St. Bonifacius, Minn.). Theclay component for litter compositions was a commercially availableBloomfield clay litter. The litter compositions were prepared in 5 poundsamples which were mixed by tumbling. Silica gel components, in theamounts of 22.7, 113.4, 226.8 and 453.6 grams were combined with 4.95,4.75, 4.5 and 4.0 pounds, respectively, of the Bloomfield clay litter toproduce 1%, 5%, 10% and 20% samples.

Fifty gram portions of each of the preparations were placed into plasticspecimen cups as were control samples consisting of the Bloomfield claylitter and 100% silica gel samples. To each of the control andsilica-gel-containing samples, 10 ml of cat urine was added and thesample allowed to stand for 24 hours. A trained panel of fourindividuals then evaluated the odors. The results are shown in Table 1.

TABLE 1 Mean % Silica Gel Raw Data Range Intensity LITTER PEARLS  0%7,6,5,4 4-7 5.5  1% 8,6,6,4 4-8 5.5  5% 5,5,5,3 3-5 4.5  10% 3,4,4,3 3-43.5  20% 4,2,3,2 2-4 2.8 100% 2,2,1,1 1-2 1.5 Desiccant Silica Gel  0%6,3,9,3 3-9 5.3  1% 5,5,7,4 4-7 5.3  5% 2,3,4,2 2-4 2.8  10% 5,3,8,4 3-85.0  20% 4,3,5,1 3-5 4.1 100% 9,1,6,1 1-9 4.3

As seen in Table 1, the compositions containing LITTER PEARLS showedincreasing odor control with increasing levels of silica gel. Thethreshold odor-controlling effect appeared at about 5% silica gel. Thedesiccant grade silica gel did not show a consistent odor controllingeffect at any concentration including 100% silica gel. Notably, thedesiccant silica gel is a Type A silica gel in contrast to the LITTERPEARLS which is a Type C silica gel. This suggests that Type C silicagel is effective in controlling odor, but Type A is not.

EXAMPLE 2

This example illustrates the odor-controlling effect silica gel at 5%,10% and 20% in a mixture with a Bloomfield clay litter.

Samples of 4.5 lbs of material were prepare from Bloomfield clay litterand 5%, 10% and 20% LITTER PEARLS. Portions of each sample were handtreated with 8-20 grams fecal cubes and 160 ml female urine on day 1.The boxes were scooped on day 6 to remove waste areas and the samplesprepared for sensory evaluation. The sensory test was scored on a scaleof 0 to 60 (weak to strong aroma) by 17 trained panelists. Samples wereplaced in 9-inch aluminum pans and covered with 8-inch pie plates.Results are shown in Table 2.

TABLE 2 Aroma Intensities¹ % Silica Gel Fecal/Urine Ammonia  0% 14.3^(A)0.6  5% 13.6^(A,B) 0.5 10% 11.7^(B,C) 0.6 20% 11.2^(C,D) 0.7 ¹Scale 0 to60, weak to strong aroma ^(A,B,) and ^(C)indicate groups that were notsignificantly different (P = 0.05)

As seen in the table, 5%, 10% and 20% tended to show a decrease in odorintensity although only the 10% and 20% samples were significantlydifferent at the 0.05 level from the control sample containing no silicagel. It is worth noting that the 5% level was also not significantlydifferent from the 10% level. No difference in ammonia intensities wasnoted among the three samples. It is concluded from this test that the5% level represents a level near the threshold amount of silica gelproducing an odor-controlling effect.

EXAMPLE 3

This example illustrates the effect of 30%, 40% and 50% silica gel mixedwith a clay litter composition.

Samples were prepared as follows: 30%, 40% and 50% silica gel inBloomfield cat litter were prepared by combining either LITTER PEARLS ofdesiccant silica gel (see Example 1) in amounts of 680.4 grams silicagel/3.5 lbs litter, 907.2 grams silica gel/3.0 lbs. litter and 1134grams silica gel/2.5 lbs litter, respectively.

Approximately 50 grams of each silica-containing sample and control wereweighed into plastic specimen cups. To each of the samples and control,10 ml of cat urine was added and the sample allowed to stand for 24hours. A trained panel of six individuals then evaluated the odors. Theresults are shown in Table 3.

TABLE 3 Frequency Ranking % Silica Gel 1st 2nd 3rd 4th LITTER PEARLS  0%5 0 0 0 30% 1 4 1 0 40% 0 2 4 0 50% 0 0 1 5 Desiccant Silica Gel  0% 2 22 0 30% 3 2 1 0 40% 0 0 1 5 50% 1 2 2 1

As shown in the table, the LITTER PEARLS tended to increase the numberranking of the samples indicating a lesser intensity of odorprogressively for 30%, 40% and 50% silica gel samples. The 30% sampledid not achieve statistical significance at the 0.05 level, however thesamples containing 40% and 50% silica gel were significantly differentfrom control (p=0.05). As noted above, the LITTER PEARLS constitute aType C silica gel.

No consistent effect was seen with the desiccant silica gel which is aType A silica gel (30% and 50% N.S.; 40% significant at p=0.05). Thisstudy further suggests that Type C silica gel such as the LITTER PEARLSis effective at concentrations up to 50% in the clay litter whereas,Type A silica gel is not consistently effective.

EXAMPLE 4

This example illustrates the effect of 0.5%, 1.0%, 2.5% and 5% silicagel mixed with clay litter.

Five samples were prepared containing 0.5%, 1.0%, 2.5% and 5% Type Csilica gel in a conventional clay litter. The samples were treated withequal amounts of cat fecal and urine. The samples were evaluated by 7sensory panelists and the rank order determined. Note that the lowestrank score indicates the least odor intensity. The results are shown inTable 4.

TABLE 4 Silica gel Rank Score   0% 3.0 0.5% 3.6 1.0% 3.0 2.5% 3.6 5.0%2.0

As shown in Table 4, the addition of silica gel at concentrations offrom 0.5% to 2.5% showed no discernable effect in reducing odorintensity. At 5.0%, however, some effectiveness in reducing odorintensity is seen.

EXAMPLE 5

This example illustrates the effects of silica gel at 2.5%, 5.0%, 10%and 20% combined conventional clay and scoopable clay from differentsources.

Type C silica gel was combined with clay litter material from differentsources to obtain concentrations of 2.5%, 5.0%, 10% and 20% with KingWilliam and Maricopa conventional litter and concentrations of 2.5%,5.0%, and 10% with Bloomfield conventional and scoopable litter. TheKing William litter is comprised of a calcium montmorillonite obtainedfrom King William, Va. and the Maricopa litter is comprised of an opalsilica and calcium montmorillonite clay mixture obtained from Maricopa,Calif. The samples were prepared and treated as in Example 4. Theresults with King William and Maricopa litters are shown in Table 5 andthe results with the Bloomfield litters are shown in Table 6. Resultsare repeated or rank sum (higher number indicates power odor intensity).

TABLE 5 Silica Gel Rank Sum King William   0% 14 2.5% 16 5.0% 15  10% 27 20% 33 Maricopa   0% 11 2.5% 20 5.0% 16  10% 28  20% 30

TABLE 6 Silica Gel Rank Sum Bloomfield Conventional    0% 16 2.5% 135.0% 19  10% 22 Bloomfield Scoopable   0% 11 2.5% 22 5.0% 17  10% 20

As shown in the table, the rank sum tended to increase with increasingsilica gel concentration for all litters tested.

EXAMPLE 6

This example illustrates the effect of 10% and 20% silica gel inconventional Bloomfield clay litter.

Samples were prepared by mixing 10% and 20% Type C silica gel withBloomfield conventional clay litter. The samples were hand treated witha one-time addition of 8 fecal cubes and 160 ml urine followed by 5 daytest period for sensory evaluation, samples were mixed thoroughly, splitand equal volumes placed in urine specimen cups. The samples wereevaluated by 19 trained panelists. The results are shown in Table 7.

TABLE 7 Aroma Intensities¹ % Silica Gel Fecal/Urine Ammonia  0% 12.9 0.410% 10.2² 0.4 20% 8.1^(2,3) 0.4 ¹Scale 0 to 60, weak to strong aroma²Significantly different from control at p = 0.1. ³Significantlydifferent from control at p = 0.05.

As shown in the table the 10% and 20% concentrations of silica geldecreased the amount of odor in the samples. No effect was, however,seen on ammonia intensity.

EXAMPLE 7

This example illustrates that fragrances can be added to 5% silica gellitter composition to control odor.

Samples of 5% silica gel were prepared with conventional and scoopableBloomfield litter. In addition, fragrance was added in powder or liquidform or as a combination of microencapsulated powder or liquid. Any of anumber of fragrances can be used of which one preferred fragrance is anherbal-pine fragrance. The samples were evaluated and the results areshown in Table 8.

TABLE 8 Intensities¹ Litter Containing 5% Silica Gel fecal/urine ammoniafragrance Scoopable Litter No Fragrance 10.1^(a) 0.4 8.2^(a) PowderFragrance 6.7^(b) 0.4 10.9^(a) Liquid Fragrance 4.1^(c) 0.4 18.7^(b)Conventional Litter No Fragrance 12.0^(a) 0.4 9.7^(a) Powder/Liquid8.5^(b) 0.6 9.8^(a) Liquid Fragrance 6.2^(c) 0.5 16.2^(b) ¹0-60 pointscale, weak to strong aroma ^(a,b,c)indicates values are significantlydifferent at p = 0.001

As seen in the table, the fragrance in either powder or liquid form wasdetected and masked fecal/urine odors in both scoopable and conventionallitter containing 5% silica gel.

EXAMPLE 8

This example illustrates the preparation of a conventional and ascoopable clay litter composition.

Conventional Clay Litter

Conventional clay litter does not clump with urine to form a scoopableagglomeration. Calcium montmorillonite clay in an amount which iscalculated to be 95% of the total weight of the litter is dried,granulated, and sized to obtain a particle size range of 0.25 to 3.4 mm.Properly sized clay granules are passed through an air ladder for airremoval of fine dust particles. The clay then passes along an additiveconveyor on which aqueous forms of additives are applied by sprayingonto the clays surface. These additives include fragrance, dust controlagents, and antimicrobial agents. The fragrance is a starch encapsulatedpowder form and/or an emulsified fragrance oil in water for sprayingonto the clay surface. Any of a number of fragrances can be used ofwhich one preferred fragrance is an herbal-pine fragrance. Theantimicrobial additive is MYACIDE or Bronopol and the dust control agentis polytetrafluoroethylene.

Type C granular silica gel having a typical granule size of 1.0 to 6.0mm particle diameter is layered onto the clay and may be sprayed withcolor agent to enhance the appearance of the product. As the conveyorbelt carries the clay with silica gel layered on top, the materialpasses stationary plows to allow mixing of the ingredients to occur. Ina similar fashion, dry powder additives can be applied such asencapsulated fragrance powders. In lieu of a conveyor system, drymaterials (clays, silica gel, and additive powders) can be blendedtogether in a screw auger, ribbon blender or other mixing devices.

Scoopable Clay Litter

Scoopable Clay litter forms clumps with urine to form a scoopableagglomeration.

Sodium bentonite clay in an amount calculated to be 80% of the totalweight of the litter is dried, granulated, and sized to a particle sizerange of 0.4-1.7 mm. and calcium montmorillonite clay in an amountcalculated to be 15% of the total weight of the litter is dried,granulated and sized to a particle size of 0.25-1.2 mm. Properly sizedclay granules pass through an air ladder for air removal of fine dustparticles. The clays are mixed and then passes along an additiveconveyor on which aqueous forms of additives are applied by sprayingonto the clay surface. These additives include fragrance, dust controlagents, and antimicrobial agents. The fragrance is a starch encapsulatedpowder form and/or an emulsified fragrance oil in water for sprayingonto the clay surface. Any of a number of fragrances can be used ofwhich one preferred fragrance is an herbal-pine fragrance. Theantimicrobial additive is MYACIDE or Bronopol and the dust control agentis polytetrafluoroethylene.

Type C granular silica gel having a typical granule size of 0.15-2.0 mmparticle diameter is layered onto the clay and may be sprayed with coloragent to enhance the appearance of the product. As the conveyor beltcarries the clay with silica gel layered on top, the material passesstationary plows to allow mixing of the ingredients to occur. In asimilar fashion, dry powder additives can be applied such asencapsulated fragrance powders and guar gum with sodium borate to aid inthe clumping. In lieu of a conveyor system, dry materials (clays, silicagel, and additive powders) can be blended together in a screw auger,ribbon blender or other mixing devices.

All references cited in this specification are hereby incorporated byreference. The discussion of the references herein is intended merely tosummarize the assertions made by their authors and no admission is madethat any reference constitutes prior art. Applicants reserve the rightto challenge the accuracy and pertinency of the cited references.

In view of the above, it will be seen that the several advantages of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above methods and compositionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limiting sense.

What is claimed is:
 1. An animal litter composition comprising a mixtureof an absorbant material and silica gel wherein the silica gel ispresent in an amount effective in controlling odor in the composition.2. The composition according to claim 1 wherein the silica gel is Type Csilica gel.
 3. The composition according to claim 2 comprising fromabout 5% to about 50% (w/w) silica gel.
 4. The composition according toclaim 3 wherein the silica gel comprises silica gel particles having anaverage pore diameter from about 8 nm to about 10 nm.
 5. The compositionaccording to claim 1 wherein the absorbant material is clay.
 6. Thecomposition according to claim 5 wherein the clay is selected from thegroup consisting of a smectite, an attapulgite, a kaolin, an opal clayand a combination thereof.
 7. The composition according to claim 6wherein the clay is a calcium montmorillonite or a sodium bentonite. 8.The composition according to claim 7 comprising from about 50% to about95% (w/w) clay.
 9. The composition according to claim 8 comprising clayparticles and silica gel particles wherein the clay particles have anaverage size and shape sufficiently similar to average size and shape ofthe silica gel particles to prevent separation of the clay particles andsilica gel particles.
 10. The composition according to claim 9 whereinthe average size of the clay particles is no more than 10% greater orlesser than the average particle size of the silica gel particles. 11.The composition according to claim 9 wherein at least 90% (w/w) of theclay comprises clay particles have a diameter of from about 3.4 mm toabout 0.6 mm and at least 90% (w/w) of the silica gel particlescomprises silica gel particles having a diameter of from about 5 mm toabout 1 mm.
 12. The composition according to claim 5 further comprisingan odor masking agent.
 13. The composition according to claim 12 whereinthe odor masking agent is a perfume, a fragrance, or an essential oil.14. A granular composition comprising clay and silica gel wherein thesilica gel is not impregnated with an odor masking agent.
 15. Thecomposition according to claim 14 wherein the silica gel is Type Csilica gel.
 16. The composition according to claim 15 comprising fromabout 5% to about 50% (w/w) silica gel.
 17. The composition according toclaim 16 wherein the silica gel comprises silica gel particles having anaverage pore diameter from about 8 nm. to about 10 nm.
 18. Thecomposition according to claim 17 wherein the clay is selected from thegroup consisting of a smectite, an attapulgite, a kaolin, an opal clayand a combination thereof.
 19. The composition according to claim 18wherein the clay is a calcium montmorillonite or a sodium bentonite. 20.The composition according to claim 19 comprising from about 50% to about95% (w/w) clay.
 21. The composition according to claim 20 comprisingclay particles and silica gel particles wherein the clay particles havean average size and shape sufficiently similar to average size and shapeof the silica gel particles to prevent separation of the clay particlesand silica gel particles.
 22. The composition according to claim 21wherein the average size of the clay particles is no more than 10%greater or lesser than the average particle size of the silica gelparticles.
 23. The composition according to claim 21 wherein at least90% (w/w) of the clay comprises clay particles have a diameter of fromabout 3.4 mm to about 0.6 mm and at least 90% (w/w) of the silica gelparticles comprises silica gel particles having a diameter of from about5 mm to about 1 mm.
 24. The composition according to claim 14 furthercomprising an odor masking agent.
 25. The composition according to claim24 wherein the odor masking agent is a perfume, a fragrance, or anessential oil.
 26. An animal litter composition comprising an absorbantmaterial and silica gel wherein the silica gel is present in an amountselected to control odor in the composition.
 27. The compositionaccording to claim 26 wherein the silica gel is Type C silica gel. 28.The composition according to claim 27 comprising from about 5% to about50% (w/w) silica gel.
 29. The composition according to claim 28 whereinthe silica gel comprises silica gel particles having an average porediameter from about 8 nm. to about 10 nm.
 30. The composition accordingto claim 26 wherein the absorbant material is clay.
 31. The compositionaccording to claim 30 wherein the clay is selected from the groupconsisting of a smectite, an attapulgite, a kaolin, an opal clay and acombination thereof.
 32. The composition according to claim 31 whereinthe clay is a calcium montmorillonite or a sodium bentonite.
 33. Thecomposition according to claim 32 comprising from about 50% to about 95%(w/w) clay.
 34. The composition according to claim 33 comprising clayparticles and silica gel particles wherein the clay particles have anaverage size and shape sufficiently similar to average size and shape ofthe silica gel particles to prevent separation of the clay particles andsilica gel particles.
 35. The composition according to claim 34 whereinthe average size of the clay particles is no more than 10% greater orlesser than the average particle size of the silica gel particles. 36.The composition according to claim 33 wherein at least 90% (w/w) of theclay comprises clay particles have a diameter of from about 3.4 mm toabout 0.6 mm and at least 90% (w/w) of the silica gel particlescomprises silica gel particles having a diameter of from about 5 mm toabout 1 mm.
 37. The composition according to claim 26 further comprisingan odor masking agent.
 38. The composition according to claim 37 whereinthe odor masking agent is a perfume, a fragrance, or an essential oil.39. A kit comprising silica gel and instructions for addition of thesilica gel to an animal litter composition in an amount effective incontrolling odor in the composition, packaged in a container.
 40. Thekit according to claim 39 wherein the silica gel is Type C silica gel.41. The kit according to claim 40 wherein the silica gel comprisessilica gel particles having an average pore diameter from about 8 nm toabout 10 mm.
 42. The kit according to claim 39 comprising instructionsfor addition of the silica gel to an animal litter composition in anamount of from about 5% to about 50% (w/w) silica gel.
 43. The kitaccording to claim 39 comprising instructions for addition of the silicagel to an animal litter composition comprising clay.
 44. The kitaccording to claim 39 comprising silica gel, an adsorbant material andinstructions for mixing the silica gel with the adsorbant material. 45.The kit according to claim 43 wherein the clay is selected from thegroup consisting of a smectite, an attapulgite, a kaolin, an opal clayand a combination thereof.
 46. The kit according to claim 45 wherein theclay is a calcium montmorillonite or a sodium bentonite.
 47. The kitaccording to claim 46 comprising instructions for mixing the silica gelwith from about 50% to about 95% (w/w) clay.
 48. The kit according toclaim 47 comprising clay particles and silica gel particles wherein theclay particles have an average size and shape sufficiently similar toaverage size and shape of the silica gel particles to prevent separationof the clay particles and silica gel particles upon mixing and furtherhandling.
 49. The kit according to claim 48 wherein the average size ofthe clay particles is no more than 10% greater or lesser than theaverage particle size of the silica gel particles.
 50. The kit accordingto claim 48 wherein at least 90% (w/w) of the clay comprises clayparticles have a diameter of from about 3.4 mm to about 0.6 mm and atleast 90% (w/w) of the silica gel particles comprises silica gelparticles having a diameter of from about 5 mm to about 1 mm.
 51. Thekit according to claim 39 further comprising an odor masking agent. 52.The kit according to claim 51 wherein the odor masking agent is aperfume, a fragrance, or an essential oil.
 53. A method for controllingodor in an animal litter, the method comprising adding silica gel to ananimal litter comprising an absorbant material, wherein the silica gelis added in an amount effective in controlling odor.
 54. The methodaccording to claim 53 wherein the silica gel is Type C silica gel. 55.The method according to claim 54 comprising adding from about 5% toabout 50% (w/w) silica gel.
 56. The composition according to claim 55wherein the silica gel comprises silica gel particles having an averagepore diameter from about 8 nm. to about 10 nm.
 57. The method accordingto claim 53 wherein the absorbant material is clay.
 58. The methodaccording to claim 57 wherein the clay is selected from the groupconsisting of a smectite, an attapulgite, a kaolin, an opal clay and acombination thereof.
 59. The method according to claim 58 wherein theclay is a calcium montmorillonite or a sodium bentonite.
 60. The methodaccording to claim 58 wherein the animal litter comprises from about 50%to about 95% (w/w) clay.
 61. The method according to claim 60 comprisingadding silica gel particles to clay particles wherein the silica gelparticles have an average size and shape sufficiently similar to averagesize and shape of the clay particles to prevent separation of the clayparticles and silica gel particles.
 62. The method according to claim 61wherein the average size of the clay particles is no more than 10%greater or lesser than the average particle size of the silica gelparticles.
 63. The method according to claim 61 wherein at least 90%(w/w) of the clay comprises clay particles have a diameter of from about3.4 mm to about 0.6 mm and at least 90% (w/w) of the silica gelparticles comprises silica gel particles having a diameter of from about5 mm to about 1 mm.
 64. The method according to claim 53 furthercomprising an odor masking agent.
 65. The method according to claim 64wherein the odor masking agent is a perfume, a fragrance, or anessential oil.
 66. A method for controlling odor in an animal litter,the method comprising selecting silica gel on the basis of the silicagel providing odor control and adding the silica gel to an animal littercontaining an absorbant material.
 67. The method according to claim 66wherein the silica gel is Type C silica gel.
 68. The method according toclaim 67 comprising adding from about 5% to about 50% (w/w) silica gel.69. The composition according to claim 68 wherein the silica gelcomprises silica gel particles having an average pore diameter fromabout 8 nm. to about 10 nm.
 70. The method according to claim 66 whereinthe absorbant material is clay.
 71. The method according to claim 70wherein the clay is selected from the group consisting of a smectite, anattapulgite, a kaolin, an opal clay and a combination thereof.
 72. Themethod according to claim 71 wherein the clay is a calciummontmorillonite or a sodium bentonite.
 73. The method according to claim71 comprising from about 50% to about 95% (w/w) clay.
 74. The methodaccording to claim 73 comprising adding silica gel particles to clayparticles wherein the silica gel particles have an average size andshape sufficiently similar to average size and shape of the clayparticles to prevent separation of the clay particles and silica gelparticles.
 75. The method according to claim 74 wherein the average sizeof the clay particles is no more than 10% greater or lesser than theaverage particle size of the silica gel particles.
 76. The methodaccording to claim 74 wherein at least 90% (w/w) of the clay comprisesclay particles have a diameter of from about 3.4 mm to about 0.6 mm andat least 90% (w/w) of the silica gel particles comprises silica gelparticles having a diameter of from about 5 mm to about 1 mm.
 77. Themethod according to claim 66 further comprising an odor masking agent.78. The method according to claim 77 wherein the odor masking agent is aperfume, a fragrance, or an essential oil.
 79. A method for making anodor-controlling animal litter composition, the method comprisingcombining an absorbent material and an amount of silica gel effective incontrolling odor.
 80. The method according to claim 79 wherein thesilica gel is Type C silica gel.
 81. The method according to claim 80comprising combining an absorbant material and from about 5% to about50% (w/w) silica gel.
 82. The method according to claim 81 wherein thesilica gel comprises silica gel particles having an average porediameter from about 8 nm. to about 10 nm.
 83. The method according toclaim 79 wherein the absorbant material is clay.
 84. The methodaccording to claim 83 wherein the clay is selected from the groupconsisting of a smectite, an attapulgite, a kaolin, an opal clay and acombination thereof.
 85. The method according to claim 84 wherein theclay is a calcium montmorillonite or a sodium bentonite.
 86. The methodaccording to claim 84 comprising combining from about 50% to about 95%(w/w) clay with silica gel.
 87. The method according to claim 86comprising combining clay particles and silica gel particles wherein theclay particles have an average size and shape sufficiently similar toaverage size and shape of the silica gel particles to prevent separationof the clay particles and silica gel particles.
 88. The method accordingto claim 87 wherein the average size of the clay particles is no morethan 10% greater or lesser than the average particle size of the silicagel particles.
 89. The method according to claim 87 wherein at least 90%(w/w) of the clay comprises clay particles have a diameter of from about3.4 mm to about 0.6 mm and at least 90% (w/w) of the silica gelparticles comprises silica gel particles having a diameter of from about5 mm to about 1 mm.
 90. The method according to claim 79 furthercomprising adding an odor masking agent.
 91. The method according toclaim 90 wherein the odor masking agent is a perfume, a fragrance, or anessential oil.
 92. A method for making an odor-controlling animal littercomposition, the method comprising selecting silica gel on the basis ofthe silica gel providing odor control and adding the silica gel to ananimal litter containing an absorbant material.
 93. The method accordingto claim 92 wherein the silica gel is Type C silica gel.
 94. The methodaccording to claim 93 wherein adding the silica gel to an animal littercontaining an absorbant material comprises adding from about 5% to about50% (w/w) silica gel to an animal litter containing an absorbantmaterial.
 95. The composition according to claim 94 wherein the silicagel comprises silica gel-particles having an average pore diameter fromabout 8 nm. to about 10 nm.
 96. The method according to claim 92 whereinthe absorbant material is clay.
 97. The method according to claim 96wherein the clay is selected from the group consisting of a smectite, anattapulgite, a kaolin, an opal clay and a combination thereof.
 98. Themethod according to claim 97 wherein the clay is a calciummontmorillonite or a sodium bentonite.
 99. The method according to claim97 wherein the clay is present in the animal litter in an amount fromabout 50% to about 95% (w/w).
 100. The method according to claim 99comprising combining silica gel particles and an animal littercontaining clay particles wherein the clay particles have an averagesize and shape sufficiently similar to average size and shape of thesilica gel particles to prevent separation of the clay particles andsilica gel particles.
 101. The method according to claim 100 wherein theaverage size of the clay particles is no more than 10% greater or lesserthan the average particle size of the silica gel particles.
 102. Themethod according to claim 100 wherein at least 90% (w/w) of the claycomprises clay particles have a diameter of from about 3.4 mm to about0.6 mm and at least 90% (w/w) of the silica gel particles comprisessilica gel particles having a diameter of from about 5 mm to about 1 mm.103. The method according to claim 92 further comprising adding an odormasking agent.
 104. The method according to claim 103 wherein the odormasking agent is a perfume, a fragrance, or an essential oil.